Add nullable : true to all properties that can have null values

[daveneti]

In OpenAPI 3.x any property that can have a null value should be marked nullable : true.

See

• https://stackoverflow.com/questions/48111459/how-to-define-a-property-that-can-be-string-or-null-in-openapi-swagger
• https://stackoverflow.com/questions/45575493/what-does-required-in-openapi-really-mean

Here are the proposed rules:

• DbIds - required and nullable: false
• PUIs - non-required and nullable: false
• Names - depends on the Entity, but if required, then nullable: false
• Other properties - See the JSON schema to see if 'null' is one of the allowed schemas.